Resistor with strip terminals



P 0, 1969 I L. E. WEYENBERG 3,470,520

RESISTOR WITH STRIP TERMINALS Filed May 18, 1967 I f/dtawzava UnitedStates Patent 3,470,520 RESISTOR WITH STRIP TERMINALS Lionel E.Weyenberg, N 35, W 23575 Capitol Drive, Pewaukee, Wis. 53072 Filed May18, 1967, Ser. No. 639,566 Int. Cl. H01c 1/14, 3/00 US. Cl. 338-302 8Claims ABSTRACT OF THE DISCLOSURE Electrical resistors are generallyformed'of wire helically wound on an insulating core. Secured around thecore and connected to each end of the Wire coil is a terminal strip, andelectrical leads are attached to each terminal strip. The use of slip-ontype connectors, which connect the leads to the terminals of theresistor, has increased substantially in recent years. The typicalslip-on connector includes a shank that is clamped to the lead wire anda head extends outwardly from the shank. The head of the connector has aflat base, and a pair of curved side members extend outwardly from thebase. The connector is adapted to be slipped on to the end of a fiatterminal, with the terminal being inserted between the base and the sidemembers and held within the connector by the frictional engagement.

To provide the necessary terminals for use with slip-on type connectors,a pair of flat prongs are generally welded to the terminal strip afterthe strip itself has been welded or otherwise secured to the core. Aterminal strip of this type has decided disadvantages'in that the stripis diflicult to assemble because it necessitates not only welding theends of the strip together to clamp the strip to the core, but inaddition, the two prongs must subsequently be welded to the strip toprovide the terminals. As a further disadvantage of the conventionalterminal strip, the current is required to pass through the weld.Furthermore, the wire coil is usually potted or encapsulated in glass orvitreous enamel, and during the firing operation at elevatedtemperatures to fuse the vitreous enamel, the welds joining the prongsto the terminal strip frequently crack or fracture.

The present invention is directed to an electrical resistance apparatus,such as a resistor or rheostat, in which the terminal prongs which areto be engaged with a slipon type of connector are formed integrally withthe terminal strip. According to the invention, the central portion orbody of the strip is bent to the contour of the core and intermediateareas of the strip at each end of the body portion are disposed flatwiseand welded together to clamp the strip to the core. The ends of thestrip project outwardly from the welded area and serve as terminals tobe inserted within the slip-on connectors.

The terminal strip construction of the invention is less costly than theconventional type in that only a single part and a single weld arerequired.

As the terminal prongs are an integral part of the strip, fracture orcracking of the prongs is minimized.

As a further advantage the current will not pass di- "ice rectly throughthe weld but instead will pass through the strip to the wound coil.

Other objects and advantages will appear in the course of the followingdescription.

The drawings illustrate the best mode presently contemplated of carryingout the invention.

In the drawings:

FIG. 1 is a perspective view of a typical electrical resistorincorporating the terminal strip construction of the invention;

1316. 2 is a transverse section through the resistor showin g theterminal strip construction;

' ,IG. 3 is an exploded plan view of the terminal strip and slip-onconnector;

FIG. 4 is an end view of the slipon connector; and

FIG. 5 is a view similar to FIG. 2 showing a modified form of theterminal strip.

The drawings illustrate an electrical resistor 1 having an insulatingcore 2, and a metal wire 3 is wound over the outer surface of the corein a spiral or helical pattern. Connected to each end of the coil 3 is aterminal strip 4 and both the coil 3 and the terminal strip 4 can becoated or encapsulated with an electrically insulating material 5, suchas vitreous enamel, resin or the like.

As best shown in FIG. 2, each terminal strip 4 is provided with acentral, generally circular body section 6 which is formed to thecontour of the core 2. Located on each end of the body portion'6 is anintermediate section 7, and the intermediate sections 7 are disposedflatwise and welded together to securely clamp the strip 4 around thecore 2.

Extending laterally from each intermediate section 7 is a section 8, andeach lateral section 8 terminates in an end or prong 9 which is disposedgenerally parallel to the intermediate section 7 but is offset laterallyfrom the corresponding section 7. Each of the terminal ends or prongs 9is adapted to be received within a slip-on type of connector 10.

As best illustrated in FIG. 3, the outer corners 11 of each prong 9 arebeveled to facilitate insertion of the prong within the connector 10,and each prong 9 is provided with a pair of shoulders 12 which serve asstops and limit the inward movement of the connector 10 on the prong.Located centrally of each prong 9 is a hole 13 which aids infrictionally retaining the connector 10 on the prong 9,

as will be hereinafter described.

The slip-on connector 10.is a conventional type and includes a tubularshank 14 which is claimed around the lead wire 15. Extending outwardlyfrom shank 14 is a head 16 which includes a flat base member 17 and apair of generally curved lateral sections 18 which extend upwardly fromthe sides of the base 17. The shank 14 is coated with a suitableelectrical insulating material 19.

The flat prong 9 of the terminal strip 4 is adapted to be insertedwithin the space between the base 17 and the lateral sections 18. Toprevent the connector from slipping from the terminal prongs 9, the base17 is provided with a pair of transverse slots 20 and a central dimple21 The slots 20 and dimple 21 act to frictionally engage the edges ofprong 9 bordering the hole 13 to thereby prevent the connector fromfreely slipping from the prong.

To fabricate the resistor of the invention, one of the terminal strips 4is initially applied to the ceramic core 2 and the sections 7 welded toclamp the strip to the core. One end of the resistance wire is thenwelded to the strip 4 and is wound around the core. Following thewinding of the coil, the second terminal strip is applied to the coreand the sections 7 of the strip are welded together. The wire coil isthen welded to the second terminal strip 4. After the welds have beencompleted, the coil 3 can be coated or potted with a suitable insulatingcoating such as vitreous enamel, resin, or the like, and fired, ifnecessary, to fuse or cure the coating.

FIG. 5 illustrates a modified form of the invention which includes aterminal strip 22, similar to strip 4 of the first embodiment. Strip 22includes a generally circular body portion 23 which is formed to thecontour of the ceramic core 2. Located at each end of the body portion23 are intermediate sections 24 which are welded flatwise together tofirmly secure the strip to the core. Extending outwardly from eachintermediate area 24 is a terminal prong 25 which is adapted to receivethe slip-on connector 10. The prongs 25 extendat an acute angle to therespective intermediate sections 24 and diverge outwardly.

The terminal strip construction of the invention is relativelyinexpensive in that a single part is required and only a single weld isnecessary to attach the strip to the core. As only a single weld isrequired, this substantially reduces the labor cost in fabricating theresistor.

As a further advantage, the terminal strip is substantially more securethan conventional types because the terminal prongs are an integral partof the strip and are therefore less likely to crack or break away duringservice.

Moreover, the current is not required to pass through the weld with thepresent terminal strip construction, but instead passes directly throughthe strip 4 between the connector 10 and the coil 3.

While the drawings illustrate the terminal strip construction as appliedto a resistor, it is contemplated that the same construction can also beutilized with rheostats and other electrical apparatus.

Various modes of carrying out the invention are contemplated as beingwithin the scope of the following claims particularly pointing out anddistinctly claiming the subject matter which is regarded as theinvention.

I claim:

1. An electrical apparatus, comprising an electrically insulating core,an electrical conductor disposed around the core, a one-piece terminalstrip connected to the conductor and including a central body portiondisposed around the core, said terminal strip also including a pair ofintermediate sections disposed at the ends of the body section anddisposed generally flatwise to each other, said terminal strip alsoincluding a pair of end sections formed integrally with the respectiveintermediate sections and extending outwardly therefrom, said end,sections being spaced apart and disposed to receive slip-on electricalconnectors, and connecting means for connecting the intermediatesections together to clamp the strip around said core.

2. The electrical apparatus of claim 1, in which the conductor is a wirecoil wound around the core.

3. The apparatus of claim 2, in which the core is gen- 4 erallycylindrical in shape and the body portion of the terminal strip isgenerally circular in cross section.

4. The apparatus of claim 1 in which said connecting means comprises aweld.

5. The apparatus of claim 1, in which the end sections are generallyfiat and are adapted to be received within a recess in said connectors,and stop means associated with said end sections to limit the receptionof said end sections with said connectors.

6. The apparatus of claim 1, in which said end sections are disposedgenerally parallel to each other and each end section is located ingenerally parallel offset relation to the respective intermediatesection.

7. The apparatus of claim 1, in which each end section is disposed at anacute angle to the respective intermediate section and said end sectionsdiverge outwardly from each other.

\ 8. An electrical apparatus, comprising an electrically I insulatingcore, a resistance wire wound around the core,

a one-piece terminal strip connected to said wire and including, acentral body portion disposed aroundthe core, said terminal stripincluding a pair of intermediate sections disposed at the ends of thebody section and disposed generally flatwise to each other, saidterminal strip clamp the strip around the core, and frictional means forpreventing free removal of the end sections from said connectors.

References Cited UNITED STATES PATENTS 995,435 6/ 1911 Bolling 338-3081,748,536 2/ 1930 Borden 338-251 I 2,709,211 5/1955 Glynn 338-322 X2,787,693 4/1957 Razlag 338-322 X 3,358,260 12/1967 Schaecher 338-302FOREIGN PATENTS 440,812 l/ 1936 Great Britain. 462,499 3/ 1951 Italy.

EQA. GOLDBERG, Primary Examiner US. Cl. X.R.

